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Active‐site mobility in human immunodeficiency virus, type 1, protease as demonstrated by crystal structure of A28S mutant
Author(s) -
Hong Lin,
Hartsuck Jean A.,
Foundling Steve,
Ermoliefe Jacques,
Tang Jordan
Publication year - 1998
Publication title -
protein science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.353
H-Index - 175
eISSN - 1469-896X
pISSN - 0961-8368
DOI - 10.1002/pro.5560070209
Subject(s) - active site , protease , proteases , mutant , hiv 1 protease , hydrogen bond , serine protease , hydrolase , chemistry , stereochemistry , serine , aspartic acid , enzyme , biology , biochemistry , amino acid , molecule , organic chemistry , gene
The mutation Ala 28 to serine in human immunodeficiency virus, type 1, (HIV‐1) protease introduces putative hydrogen bonds to each active‐site carboxyl group. These hydrogen bonds are ubiquitous in pepsin‐like eukaryotic aspartic proteases. In order to understand the significance of this difference between HIV‐1 protease and homologous, eukaryotic aspartic proteases, we solved the three‐dimensional structure of A28S mutant HIV‐1 protease in complex with a peptidic inhibitor U‐89360E. The structure has been determined to 2.0 Å resolution with an R factor of 0.194. Comparison of the mutant enzyme structure with that of the wild‐type HIV‐1 protease bound to the same inhibitor (Hong L, Treharne A, Hartsuck JA, Foundling S, Tang J, 1996, Biochemistry 35 :10627‐10633) revealed double occupancy for the Ser 28 hydroxyl group, which forms a hydrogen bond either to one of the oxygen atoms of the active‐site carboxyl or to the carbonyl oxygen of Asp 30 . We also observed marked changes in orientation of the Asp 25 catalytic carboxyl groups, presumably caused by the new hydrogen bonds. These observations suggest that catalytic aspartyl groups of HIV‐1 protease have significant conformational flexibility unseen in eukaryotic aspartic proteases. This difference may provide an explanation for some unique catalytic properties of HIV‐1 protease.